A display device that displays a stereoscopic image using a binocular parallax is known. Such a display device is configured to display, on one screen, an image to be seen from the position of the left eye of a viewer (an image for left eye) and an image to be seen from the position of the right eye of the viewer (an image for right eye). The viewer sees the image for left eye with the left eye and the image for right eye with the right eye and is thus allowed to see a stereoscopic image.
For example, in a glasses system, an image for left eye and an image for right eye are alternately displayed on a screen of a display device in synchronization with a shutter provided in a pair of glasses, whereby the left eye of a viewer is allowed to see only the image for left eye and the right eye of the viewer is allowed to see only the image for right eye. Thus, the viewer can see a stereoscopic image.
Further, in a display device using a parallax barrier system which allows a viewer to see a stereoscopic image with naked eyes, a screen is divided into many regions (e.g., strip-like regions). The regions are alternately allocated to the region for right eye and the region for left eye, and a parallax barrier is provided to overlap with the boundaries of the regions. In each the divided region, an image for right eye is displayed on the region for right eye, and an image for left eye is displayed on the region for left eye. With the parallax barrier, the regions for displaying the image for right eye are hidden from the left eye of a viewer and the regions for displaying the image for left eye are hidden from the right eye of the viewer; consequently, the left eye is allowed to see only the image for left eye and the right eye is allowed to see only the image for right eye. Thus, the viewer can see a stereoscopic image with the naked eyes.
Note that a display device including a switchable parallax barrier for achieving switching between a flat image display mode and a stereoscopic image display mode is known (Patent Document 1).
In addition, a light-emitting element in which a layer containing a light-emitting organic compound is provided between a pair of electrodes is known. This light-emitting element is a self-luminous type; therefore, high contrast and high speed of response to an input signal are achieved. A display device to which this light-emitting element is applied is known (Patent Document 2).